The present disclosure relates to an arrangement including a master controller and a slave controller which are interconnected for exchanging data with each other via a communication line. The present disclosure also relates to the master controller and the slave controller.
Components in the motor vehicle which are controllable via a central controller, hereinafter master controller, and which operate at a reference voltage differing from the reference voltage of the master controller, each require separate power supply lines and ground connections in order to ensure that fault currents into the master controller are prevented in the event of a loss of ground, in the event of short circuits, or due to reversed polarities.
For the communication with the master controller, such components each have a transceiver unit, wherein the transceiver unit communicates with the transceiver unit of the master controller. In addition, such components include a consumer, for example, a positioning drive for a seat, a windshield wiper, a tailgate, or a window. Furthermore, such components include a device controller which is provided for the control of the consumer as a function of the data transmitted by the master controller.
In most cases, multiple such components are connectable to the master controller. In this case, the communication between the components and the master controller, i.e., which device accesses the communication line at which time, is controlled via a protocol in which the master controller in most cases acts as the master and the components in most cases act as slaves. Therefore, an electrical portion of each of the components, which includes its transceiver unit and its device controller, is hereinafter referred to as a slave controller.
A master controller conventionally functions at a 12V on-board electrical system voltage as the reference voltage. It provides the slave controllers, which often operate at a reference voltage of 12V, 24V, or 48V, with a pulse width modulated (PWM) communication signal for the communication via the communication line, which includes control commands for controlling the consumers.
In order to prevent fault currents which may damage the master controller, the connection of slave controllers which use a reference voltage other than that of the master controller has previously been allowable only via galvanic isolation.
FIG. 1 shows an arrangement having a first specific embodiment of a slave controller and a master controller, in which both the master controller and the slave controller use a 12V on-board electrical system voltage as the reference voltage. Therefore, in this specific embodiment according to the related art, no galvanic isolation is required.
FIG. 2 shows an arrangement according to the related art having a second specific embodiment of a slave controller which uses a reference voltage different from that of the master controller, for example, a 24V or 48V reference voltage instead of the 12V reference voltage. In order for no fault currents to be able to flow from the slave controller to the master controller in the event of a ground loss, due to short circuits, or due to reversed polarity, the transceiver unit of the slave controller is galvanically isolated from its device controller operating at the other reference voltage, for example, via optical couplers (not shown).
However, the use of galvanic isolation is expensive and requires extensive installation space.